Smitten fans were also directed to videos saying the 16-year-old pop star had died in a car accident.
Hackers changed the sound on one video to a voice-over falsely reporting that the teenager had died, while other YouTube pages featured pop-up windows of pornography websites and explicit videos.
A report in the Daily Telegraph said Internet forum 4Chan is believed to have been responsible for the attacks, but other mischief makers apparently joined in once the hacks were discovered.
YouTube said it was working to fix the problem as soon as possible.
This is not the first time the Beeb has been the focus of a hoax. He has already had to fend off rumours that he is Chuck Norris’ son and that he has joined a cult.
He recently Tweeted, "I am not the son of CHUCK NORRIS ... and I have not joined the Illuminati or any other cult.